Thermal activation and deactivation of grown‐in defects limiting the lifetime of float‐zone silicon
Thermal activation and deactivation of grown‐in defects limiting the lifetime of float‐zone silicon
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生长缺陷的热激活和失活限制了区熔硅的寿命
DOI：
10.1002/pssr.201600080
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
D. Macdonald
中科院分区：
文献类型：
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作者：
N. Grant;V. Markevich;J. Mullins;A. Peaker;F. Rougieux;D. Macdonald
通过研究五家领先供应商最近生产的商用n型和p型浮动区(FZ)硅的少数载流子寿命，我们观察到FZ硅在450-700°C范围内热处理时，体寿命有很大的缩短。在晶片规模上对这些样品的光致发光成像显示出同心圆图案，在中心发生更高的复合，而在外围发生更少的复合。深能级瞬变谱测量表明存在复合活性缺陷，包括一个能级为∼eV+0.5 eV的优势中心。当FZ硅在氧气中于>；1000°C进行热处理时，寿命完全恢复，因此缺陷消失，并且在随后的500°C热处理时不再出现。我们得出结论：在>；1000°C的热处理导致复合活性缺陷的完全消失。如果没有这样的高温处理，FZ硅中的少数载流子寿命是不稳定的，并将影响高效(>；24%)太阳能电池和表面钝化研究的发展。
By studying the minority carrier lifetime in recently manufactured commercially available n‐ and p‐type float‐zone (FZ) silicon from five leading suppliers, we observe a very large reduction in the bulk lifetime when FZ silicon is heat‐treated in the range 450–700 °C. Photoluminescence imaging of these samples at the wafer scale revealed concentric circular patterns, with higher recombination occurring in the centre, and far less around the periphery. Deep level transient spectroscopy measurements indicate the presence of recombination active defects, including a dominant center with an energy level at ∼Ev + 0.5 eV. Upon annealing FZ silicon at temperatures >1000 °C in oxygen, the lifetime is completely recovered, whereby the defects vanish and do not reappear upon subsequent annealing at 500 °C. We conclude that the heat‐treatments at >1000 °C result in total annihilation of the recombination active defects. Without such high temperature treatments, the minority carrier lifetime in FZ silicon is unstable and will affect the development of high efficiency (>24%) solar cells and surface passivation studies.